1. Field of the Invention
The present invention relates generally to right-angled coaxial cable connectors, and particularly to right-angled coaxial cable connectors that have fewer components and may be sealed for outside use.
2. Technical Background
Coaxial cable connectors such as F-connectors are used to attach coaxial cables to another object such as an appliance or junction having a terminal adapted to engage the connector. The coaxial cable typically includes a center conductor surrounded by a dielectric, in turn surrounded by a conductive grounding foil and/or braid; the conductive grounding arrangement is itself surrounded by a protective outer jacket. The F-connector is secured over the prepared end of the jacketed coaxial cable by use of a crimp or compression tool specifically designed to actuate the F-connector. Once secured to the coaxial cable, the F-connector is then capable of transferring signals by engaging a threaded connection found on typical CATV electronic devices such as set top converters, television sets or DVD players.
Crimp style F-connectors are known wherein a crimp sleeve is included as part of the connector body. A special radial crimping tool, having jaws that form a hexagon, is used to radially form the crimp sleeve around the outer jacket of the coaxial cable to secure such a crimp style F-connector over the prepared end of the coaxial cable. An example of such a crimp connector is disclosed within U.S. Pat. No. 4,400,050 to Hayward.
Crimping braided outer conductors is problematic. To prevent deformation of the outer conductors in relation to the center conductor, a support sleeve of one form or another may be used. Usually, the braid is captured in a layer between a tubular outer ferrule and the connector body. This crimp is not considered highly reliable. There are typically large voids in the interface allowing for corrosive degradation of the contact surfaces. The mechanical pull strength of the joint does not approach the strength of the wire. Finally, the connection allows relative movement between all 3 components, which results in a very poor, noisy electrical connection.
Another form of an F-connector is known wherein an annular compression sleeve is used to secure the F-connector over the prepared end of the cable. Rather than forming a crimp sleeve radially toward the jacket of the coaxial cable, the F-connectors employ a plastic annular compression sleeve that is initially attached to the F-connector, but which is detached therefrom prior to installation of the F-connector. The compression sleeve includes an inner bore for allowing the compression sleeve to be passed over the end of the coaxial cable prior to installation of the F-connector. The F-connector itself is then inserted over the prepared end of the coaxial cable. Next, the compression sleeve is compressed axially along the longitudinal axis of the connector into the body of the connector, simultaneously compressing the jacket of the coaxial cable between the compression sleeve and the tubular post of the connector. An example of such a compression sleeve F-connector is shown in U.S. Pat. No. 4,834,675 to Samchisen; the patent discloses a compression sleeve type F-connector known in the industry as “Snap-n-Seal.” A number of commercial tool manufacturers provide compression tools for axially compressing the compression sleeve into such connectors.
Standardized cable preparation tooling and connector actuation tooling have led to a defacto standard in cable preparation dimensions and connector envelope configurations. Additional requirements for both indoor and outdoor use have resulted in connector designs that require a relatively large number of components. Often times these standardized connector and tooling systems are used to manufacture CATV jumper cables in large quantities, causing unnecessary expense to be incurred in the manufacture of CATV jumper assemblies.
Many of the applications noted above employ the use of straight connectors (the longitudinal centerline of the connector is coaxially aligned with the longitudinal centerline of the coaxial cable). There are also applications where the use of a right angle version of the coaxial connector is advantageous. The construction of right angle connectors is typically more complex than the construction of straight connectors because of the difficulty of maintaining mechanical and electrical characteristics of the coaxial structure around a right angle bend. Typically, a fabricated center conductor is captured within the connector body and insulated with various dielectric configurations. Use of this type of approach necessitates a relatively high number of components compared to straight connectors. Additionally, in right angle connectors, it is difficult to achieve comparable electrical performance to that of a straight connector due to interruptions along the center conductor path.
Regardless of the method used to secure the coaxial cable to the F-connector, the F-connector virtually always includes a rotatable nut for securing the F-connector to a threaded port. For F-connectors that are used exclusively indoors, the coupling nut can be free-spinning, as there is no need to create a moisture barrier between the coupling nut and other components of the F-connector. However, it is known in the art that the passage of moisture inside the F-connector can lead to corrosion, increased contact resistance, reduced signal strength, and excessive RF leakage from the connector. Accordingly, when such F-connectors are used outdoors, those skilled in the art have made various efforts to form a seal between the various components of the F-connector, including the joint between the coupling nut and the coupling nut retainer of the F-connector.
For example, the practice of incorporating one or more resilient O-rings between various components of the F-connector has been used to seal out moisture. In U.S. Pat. No. 5,338,225 to Jacobsen, et al., an O-ring is positioned inside the coupling nut just ahead of the tubular post adjacent the internally threaded bore of the nut. However, in this case, the O-ring is contacted by the threaded post and can be degraded by such contact. Moreover, the O-ring is always bearing against both the coupling nut and the end of the tubular post, creating a drag effect that resists rotation of the coupling nut.
It is also known to dispose an O-ring near the opposite end of the coupling nut, trapped between a rearwardly-directed collar of the nut and the cylindrical body portion of the F-connector; such a structure is shown, for example, in U.S. Pat. No. 4,834,675 noted above. During assembly of the connector, the O-ring is pre-compressed between the coupling nut and the cylindrical body to create a seal therebetween; as in the prior example, the O-ring constantly engages both the nut and the cylindrical body and creates drag that resists rotation of the nut. Furthermore, the forces created as the coupling nut is tightened over a threaded post or terminal have no impact on the degree of seal created between the coupling nut and the cylindrical body, i.e., further tightening of the coupling nut over the threaded terminal does not increase the amount of compression of the O-ring. In addition, the creation of the rearwardly-directed collar within the coupling nut increases manufacturing costs because the coupling nut must be machined from both ends.
In most cases, a coaxial cable service technician threads the coupling nut over a threaded terminal by hand, until the nut is hand-tight. The technician then uses a wrench to make a final turn to secure the nut over the threaded terminal. The continuous drag applied by such O-rings to the coupling nut is a nuisance to service technicians, as compared with indoor-type free-spinning coupling nuts because it is more difficult to rotate the coupling nut as it is being hand-tightened over the threaded post.
Therefore, a right angle coaxial cable connector with a reduced number of components that maintains the mechanical and electrical characteristics of the coaxial structure and has a seal for outdoor use is desired.